1. Technical Field
The present invention relates to an integrated circuit device, an electronic device, an electronic apparatus, and a base station.
2. Related Art
Stable output frequencies with higher accuracy to temperature changes are required for crystal oscillators used for reference frequency signal sources for communication apparatuses or measuring instruments. Generally, oven controlled crystal oscillators (OCXO) are known as crystal oscillators with extremely high frequency stability.
The OCXO houses a quartz crystal vibrator within a thermostatic oven controlled at a constant temperature. For example, Patent Document 1 (JP-A-2015-122426) discloses an OCXO in which a vibrator element, a heat generation IC, and an oscillation IC are housed within a package.
The heat generation IC of Patent Document 1 includes a semiconductor substrate on which a diffusion layer is formed, a pad for application of a power supply voltage to the diffusion layer, and a pad for application of a ground voltage to the diffusion layer. An insulating layer is formed on the diffusion layer, and a surface protective film is formed on the insulating layer. Opening portions are formed in the surface protective film and the rectangular pads are formed on the surface of the insulating layer in the opening portions.
However, in the heat generation IC of Patent Document 1, the opening portions are formed in the surface protective film and the pads are formed within the opening portions, and steps are formed by the surface protective film and the pads. The steps may hinder wire bonding to the pads. For example, when the positions of the opening portions shift due to manufacturing errors or the like, the capillary used for wire bonding may collide with the steps formed by the surface protective film and the pads.